Individual brain cells can identify both cars and cats

Published: Thursday, June 10, 2010, 15:11 [IST]

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Washington, June 10 (ANI): Single brain cells, if confronted with a difficult task, can identify objects as dissimilar as sports cars and dogs, found researchers at MIT's Picower Institute for Learning and Memory.

Researchers have never been sure exactly how specialized cells in the brain can be.

They always wondered if different neurons each contribute to unique thoughts or if some neurons can be cognitive "generalists" and participate in multiple thoughts.

To answer this, researchers examined the prefrontal cortex, the brain's executive in charge of decision-making and planning.

In previous studies, Earl K. Miller found that individual neurons in monkeys' brains could become tuned to the concept of "cat" and others to the concept of "dog."

This time, the researchers recorded activity in the monkeys' brains as the animals switched back and forth between distinguishing cats vs. dogs and sports cars vs. sedans.

Although they found individual neurons that were more attuned to car images and others to animal images, to their surprise, there were many neurons active in both categories.

In fact, these "multitasking" neurons were best at making correct identifications in both categories.

The study suggests that cognitive demands-how much brainpower is needed for a particular task-may determine whether neurons in the prefrontal cortex "multitask" or stick to specialized categories.

"This ability to 'multitask' allows the brain to re-utilize the same pool of neurons for different tasks. Without it, storage capacity for critical thought might be severely limited," said Miller.

The work could lead to a better understanding of disorders such as autism and schizophrenia in which individuals become overwhelmed by individual stimuli.

For instance, a person with autism, when asked to picture a dog, may be flooded with dozens of mental images of all the canines he had ever seen.

In the study, researchers investigated how the prefrontal cortex encodes multiple, independent categories in monkeys trained to randomly alternate between performing two category problems.

Wearing devices that allowed researchers to identify activity in individual neurons, the monkeys were presented with morphed images, such as that of a sports car with attributes of a sedan or a cat with attributes of a dog.

If the image was more than 50 percent like a sports car or a cat, the monkeys had to identify it as such to get a reward. The monkeys scored correctly 80 percent of the time.